Brake



p 4- I L.. K. SNELL 1,974,589

' BRAKE Fled Dec. 20, 1929 Patentecl Sept. 25, 1934 UNITED STATES PATENT- OFFICE BRAKE Lyle K. Snell, Detroit, Mich., assignor tu Ea.ton

Manufacturing Company, Cleveland, Ohio, a corporation ot Ohio Application December 20, 1929, Serial No. 415,395

15 Claims. (01. 188-78.

Thls invention relates generally to vehcle In the accompanying sheet of drawing, brakes, and has particular reference to un im- Fig. 1 is a side elevational view showing the arproved form of brake having the parts thereof rangement of partis with the brake drum in secconstructed and arrangecl so as to attainmaxiton;

I mum eflciency and length of life of the bra.ke Fig. 2 is a cross-section taken on line 2-2 of 6 lining. Fig. 1; and

In vehcle brakes, a.s heretofore constructed, it Figs. 3, 4 and 5 are diagrammatic illustrations has been the general practice to ma.ke end. assemof certain geometrical truths. ble the brake shoes so that the curved surfaces In vehcle brakes embodying the principles 01 0 thereof, to which the brake lining is attachd, are my invention, the cooperating surfaces of the substantially concentric with the curved surface brake shoes and brake drum are so shaped end arof the bra.ke drum, tha.tis to say, that in the conranged that the most efficent use of the brake struction and arrangment of these parts, the lning is attained throughout the life of the brake. space for the brake lining is provided by making' In Figs. 1 and 2 of the drawng illustrating my in- 6 the curved surfa.ce of the brake shoe of a. radius vention, I have shown one form of brake to which 7 which is smaller than the radius of the drum by this principle may be applied, but it should be an amount approximately equal to the thickness understood, however, that my invention is not of the lining. 'I'hus the brake lning;as heret-olimited in its application to any particolar Iorm Iore used, has been uniform in thickness with the of brake, but may be embodied in brake construc- 1) radius of curvature of its drum engaging surface, tions of various types regardless of whether the greater than the radiu.s of its shoe engaging surshoes are individually pivoted or are 01 the free tace. In the operation of these brakes.,as heretofloating type. fore constructed with lining of unifonn thickness In order thai. my invention may be more readand with shoes ha.ving a. radius o! curvature which ily understood, and the scope of its useful appli- 5 13 diflerent from the radius of the drum, certain cation more fu1ly appreciated, reference is made portionsot the surtace of the lining are pressed to certain geometrical truths. upon which the against the drum surface with greater torce tha.n principles of my invention are based, and which are other portions of its surfa.ce, with the result govern the movements of curved surfaces, such as' thai: those portions under greater pressare wear cooperating braking surfaces,- into engagement o away more rapidly and may be completely wom with ea.ch other. One of the geometrical truths avvay end expose the surtace 01' the brakeshoe to which I refer is illustrated diagrammatically while other Dortions 01 the lining are still servicein Fig. 3. and teaches that when an arcuate sur- -able. 'Ihis rapid wearing aws;y of certan porfa.ce 10, lyiug within an annular surface 11 o! tions of the lining renders the brake less eflisient greater radius, moves bodily into conta.ct with 5 end makes necessary frequent renewals 01 the the annular surface, the initial point of tanlining. gency 12 between the surfaces will be a.t approxi- It is, therefore, an object of this invention to mately the mid-portion of the arcuate surface. providea. brake ha.ving the parts thereof con- F'rom this statement of fact, ii: follows obvlously structed ami arranged to provide a 1in.ing thickthat, with the mid-portion of the arcuate surtace o ness at any point which will be substantially protangent to the annular surfa.ce, the end. portions portional to the rate of liningwear at tbat point. 13 of the arcuate surface will be in sx'aaced rela- Another object of this invention is to provide a. tion to the annular surface. On the other hand, brake in which the usell and eflcient lite 01 the as illustrated in Fig. 4, 11 the radius of the arcubrakelining is prolonged by providing increased ate surface 14 is greater than the radius of the 5 lining thicknes's al: those points where lining wea.r annular surface 15 within which it lies, the inioccurs most rapidly. tial points of tangency, when the arcuate surface A further object of this invention is to provide is moved bodily into contact with the annular a. form of'brake in which the wearing life of the surface, will be at the end portions 16 of the intermedite portons of the brake lining will be arcuate surface, while its mid-portion 17 will be 0 substantially the same as the wearing.lite of the spaced from the annular surfa.ce. Another of end portions of the brake lining. these geometrcal truths is illustrated in Fig. 5,

The invention may be further briefly summaa.nd teaches that when an arcuate surfa.ce 18 is rized as consisting in certain nove! combinations arranged within an annular surface 19 of the and-arrangements of parts hereinaftexdescribed saune radius and spaced therefrom, the mici-pora.nd partlcularly set outinthe appende'cl claims. tion 20 01 the arcuate surface will be spaced said shoe having a, curved surface of the same radus as the curved surface of said drum; and

brake linng interposed between said curved surfaces, said lining being shaped m conform to the curvature of said surfaces.

-2. A brake comprisng a rotatable drum having a curved surface, a substantially rigid brake shoe arranged tor cooperation with sad drum, said shoe having a curved surface of the same radius as the curved surface of said drum, and a section of brake lning having apposite surfaces thereof curved to the same radius, one side of said lining being in contact with the curved surf%e of said shoe and the other side cf saio lining being presented for contact with the curvec surface of said drum.

3. A brake comprisng a rotatalcle drum havng a curveol surface, a brake shoe arranged for cooperation with sac drum and havng a curved surface of the same radius as the curved surface of saicl drum, and bralre lining securec to the curved surface of said shoe tor engagement with the curved surface of said drum, the centers far the radii of said curved surfaces being spaced apart a distance which is equal to the desirecl maximum thickness cf said linng, when the 1ming contacts wth both cf said surfaces and s in an unworn. conditon.

4. A brake compr-sng a rotatable drum. having a curved surface, a substantally rigid brake shoe arranged for ccoperation with said drum and having a. curved surface of substantially the same radius as the curved surface of said drum, and a substantially crescent-shaped secticm of brake lining held against the curved surface of said shoe tor cooperation with the curved surface of said drum.

-5. A brake comprsing a. rotatable drum baving a curved surface, a supportng member ad.-

jacent sad drum, a brake shoe pivoted on. said supporting member for cooperation with said drum and having a curved surface of substantially the same radius as the curved surface of sad drum, and a substantially crescent-shaped section of brake lining held against the curved surface of said shoe tor cooperation with the curved surface of said drurn.

6. A brake comprising a rotatable drum having a curved surface, a brake shoe arranged for cooperaton with sa.id drum and having a curved surface of substantially the same radius as the curved surface of 'said drum, and brake lining interposed between said curved surfaces, said brake 1ining having an intermediate portion of maximum thickness and being tapered from saidl maximum thicknesso a minimum thickness ai;

its ends whereby the thickness of the lining at any point is substantially prcportional to the rate of Wear ai: thai; point.

7. A brake comprising a. rotatable drum having a curved surf-ace, a train of brake shoes ar ranged circumferentially of said drum for cooperation therewith, each shoe of said train having a curved surface of the same radius as the curved surface of said drum, and brake linng interposed between said curved surfaces, said lining being shaped to conform to the curvature of said surfaces.

8. In a brake structure, a. stationary base, a

and than at its center.

brake drum, a shoe pivoted ah one of its ends to a. point on said base located on a radius of the drum which is at substantally right angles to a line extending between the center of the brake shoe and the center of the brake drum, the surface of said shoe being formed on the same radius as the braking surface of the brake drum, a lining on said shoe and means for imparting swinging movement to said shoe.

9. In a brake structure, a stationary base, a brake drum, a brake shoe pivoted ai; one of its ends tu said base, the surface of said shoe being farmaci on the same radus as the braking surface of the brake drum, and a lining on said shoe thicker ah its center than at its ends.

10. In braking apparatus, the combination With a brake drum, of a pivotally mountd brake shoe Wth brakc lining secured thereon, the brake lining carrying portion 01 the shoe having the same radius cf curvature as the braking surface of the drum.

11. In braking apparatus, the combination With a brake drum, of a pivotally mounted brake shoe having a brake lining carrying surface of the same radus of curvature as the braking surfuce of the drum, and a, brake Iinng thereon whose drum engaging surface has the same radius of curvature as the braking surface of the drum.

12. In hraking apparatus, the combnation with a biake drum haviug an internal cylindrical braking surface, of a brake shoe pivotally supported at one end and having a brake lining secured thereto, the lining carrying surface of he shoe and the drum engaging surface of the lining each having the same radius of curvature as the braking surface of the drum.

13. In braking apparatus, the combination with a brake drum, of a brake shoe pivotally supported at one end and provided with a fricton element te engage the drum and destructible by 115 braking wear, the portion of the shoe carrying the fricton element having substantially the same radius of curvature as the braking surface of the drum, and the pivot of the shoe being so positioned that in the absence 01 the fricton 129 element the axis of the curvature of the aforesaid portion of the shoe, when said portion is in contact wth the drum, approximately coincides with the axs cf curvature of the braking surface of the drum.

14. In braking apparatus, the combnatio With a. brake drum having a cylindrcal braking surface, of a brake sh e adapted to cooperate therewth and having a brake lining carrying surface of. substantially the same radius ci curvature as the brakng surface of the drum, and a brake lining thereon whose operative portion is ci non-uniform thickness, being thinner at its ends than intermediate thereof.

15. In braking apparatus, the combination Wth a brake drum having a cylindrical braking surface, of a brake shoe adapted to cooperate therewu'thand having a brake lining carrying surface of substantially the same rac'lus of curva.- ture as the braking surface of the drum, and a brake lining thereon whose operative portion is of non-uniform thickness, being thinner at one LYLE K. SNELL. 

